The invention relates to a wide-meshed, textile lattice to provide reinforcement for bitumen-bonded layers, in particular for road surface.
The lattice essentially consists two sets of parallel, load-bearing threads, whereby one set of threads extends in the longitudinal direction of the lattice and the other set of threads extends transversely to the longitudinal direction of the lattice and the threads are made from glass fibers or chemical fibers such as polymer fibers or polycondensate fibers and are Raschel-locked onto a fleece, whereby the connecting Raschel-locking threads surround the longitudinally extending threads of the lattice and secure the transversely extending threads.
The lattice may be woven or Raschel-locked but alternatively the load-bearing parallel threads running transversely to the longitudinal direction may be laid on the load-bearing parallel threads and bonded to the longitudinal threads at the intersecting points by bonding and welding.
A lattice bonded to a fleece of this type is known from publication EP 0 413 295 A. The geo-textile used for reinforcing layers of asphalt known from this publication is a bonding material consisting of two components, one of these components being a fleece and a second of these components a woven fabric, knitted fabric, thread pattern, lattice or any other flat layout having a defined yarn position. The bonding material is provided as a Raschel-locked material in which the two components are integrated one in the other by means of an end-latching Raschel technique. The fleece is designed to have a good capacity for absorbing bitumen so that when the geo-textile is laid down, this fleece becomes impregnated with bitumen and acts as a barrier to water. The fleece is also intended as a means of preventing the occur rence of tearing and the propagation of tearing in the layers of asphalt. The weight of the fleece by surface area should be 50 to 300 g/m2, preferably 100 to 180 g/m2. This geo-textile forms a separating layer in the installed state.
DE 20 00 937 discloses a wide-meshed textile lattice for reinforcing road surfacing, which is pre-fabricated so that it is coated with a specific bonding substance having an affinity to bitumen, e.g. a bitumen-latex emulsion, in order to produce a good adhesion between the lattice and the bitumen bonded layers.
In order to obtain a firm bond between the layers of the road surfacing on the two sides of the reinforcing lattice, there is an advantage to be had if the lattice is made with a wide mesh so that the distance between the parallel threads in the longitudinal direction and those in the transverse direction is 20 to 100 mm. The mesh width should be determined on the basis of the largest grain diameter of the surfacing mixture to be used. Advantageously, the mesh width is 2 to 2.5 times greater than the largest grain diameter. The load-bearing threads in the longitudinal and transverse directions should have a breaking strength of from 10 to 100 kN/m. If necessary or desirable, even stronger threads can be used for the reinforcing lattice.
As a result of the coating of bonding substance, the lattice is of a semi-rigid consistency. The lattice, which is 5 m wide and 30 or 50 m long, for example, is rolled out onto a surface which has been evenly sprayed with a bonding compound or bitumen emulsion. The reinforcing lattice should be laid out flat and free of folds before any further surfacing mixture is applied to the reinforcing lattice. In the case of these known lattices, a difficulty arises in that once rolled out, the reinforcing lattice slides causing creases, particularly when vehicles are driven over the laid-out lattice.
It is therefore desirable to develop a reinforcing lattice for bitumen-bonded layers which does not act as a separating layer between these layers and which provides better bonding than the known lattices on a pre-prepared road level.
In general, according to one aspect of the invention, the fleece has a weight of 10 to 50 g/m2 and that the load bearing threads are treated and coated together with the fleece, with a bonding substance having an affinity to bitumen, the fleece having openings in the coating of bonding substance and being perforated in order to be permeable to air.
Due to the fact that the mesh of the lattice is filled with a thin fleece, a significantly stronger bond is produced when the lattice is laid on the formation. On the other hand, the fleece is so thin and consequently so flexible that the fleece does not act as a separating layer between the asphalt layers underneath and above the lattice. In spite of the existence of the fleece, nevertheless a firm keying action between the coarse grains of the surfacing mixture laid on top of the lattice and the coarse grains of the surfacing mixture underneath the lattice is achieved.
Due to the fact that the load-bearing threads of the lattice in the direction of the warp are lashed by the Raschel locking threads, the load-bearing threads running at right-angles thereto are fixed at their respective distances from one another. In
another variant of the embodiment of the invention, there is no need for the lattice to be impregnated or coated with a bonding compound having an affinity for bitumen if the load-bearing threads are made from a polymer or a polycondensate, which in itself provides a firm bond with bitumen.
Furthermore, the underside of the composite of the textile lattice and the thin fleece may be provided with a bituminous mastic. This bituminous mastic melts when the hot asphalt mixture needed to form the bituminous surfacing is deposited on the laid lattice matting. It is advantageous to apply the bituminous mastic only in spots or stripes parallel with the winding axis in order to preserve the flexibility of the reinforcing lattice. The quantity of the bitumen-latex emulsion to be sprayed on the road level.
Due to the fact that the load-bearing threads of the lattice in the direction of the warp are lashed by the Raschel locking threads, the load-bearing threads running at right-angles thereto are fixed at their respective distances from one another.
According to another embodiment of the invention, there is no need for the lattice to be impregnated or coated with a bonding compound having an affinity for bitumen if the load-bearing threads are made from a polymer or a polycondensate, which in itself provides a firm bond with bitumen.
Furthermore, the underside of the composite of the textile lattice and the thin fleece may be provided with a bituminous mastic. This bituminous mastic melts when the hot asphalt mixture needed to form the bituminous surfacing is deposited on the laid lattice matting. It is advantageous to apply the bituminous mastic only in spots or stripes parallel with the winding axis in order to preserve the flexibility of the reinforcing lattice. The quantity of the bitumenlatex emulsion to be sprayed on the road level is considerably reduced by the bituminous mastic on the composite and may even be omitted completely. The installation of the lattice is simplified and the time for installing the reinforcement is reduced. The quantity of the mastic to be applied depends on the condition of the asphalt or road surfacing to be renewed. It ranges preferably from 150 g to 500 g/m2.
The description given below, in conjunction with the appended drawings, provides an explanation of an embodiment of the invention. Of the drawings,